HOUSTON -- As the Astros continue their push toward the postseason, two contributors from last year's playoff squad, outfielder Colby Rasmus and pitcher Luke Gregerson, are seeking to return from their injuries sooner rather than later.

Rasmus has been making a great deal of progress since undergoing surgery on his right ear Aug. 12 to remove a cyst -- a major part of why he's been in a 2-for-70 slump since July 1. The 30-year-old has been working out with the team since Friday.

Astros manager A.J. Hinch said Rasmus, who had a day off on Sunday, will get a full workload in Monday. How he performs then will factor into whether or not he needs a rehab assignment before returning.

"As a veteran player, I think he could possibly not need a rehab assignment, because we would want him back so quickly with rosters expanding on Thursday," Hinch said. "But we've got to make that determination in a physical sense [on Monday] after his workout."

Hinch said he needs to be sure Rasmus, a career .241 hitter, has his legs and baseball timing back before he returns to the fold.

"I don't want another hamstring issue," Hinch said. "I think that's the biggest issue when you sit a couple weeks: your timing at the plate and your legs being able to pound every day for nine innings. [With] as much ground as we expect our outfielders to cover, I'm going to need to feel pretty comfortable that his legs are in shape and that his swing path is efficient enough to jump right into games."

Gregerson shuts the door

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As for Gregerson, his return timetable appears a little more uncertain. Gregerson has been battling a left ankle injury the last couple of weeks, and he hasn't pitched since Aug. 18. The right-hander has been dominant in the eighth inning of games this season, posting a paltry 0.64 ERA

"He's still hobbling around," Hinch said.

Gregerson was unavailable for Houston's 6-2 win Saturday night, but hasn't been on the DL because Hinch didn't want him to miss an extra few games if he doesn't have to.

Ideally, the Astros would like to get Gregerson into a game sometime during Houston's three-game home series with the A's, but the nature of the injury makes it a little iffy.

"It's not his arm," Hinch said. "He's in shape. He's been throwing off the mound a couple of times. We're worried a little bit about him covering first and breaking in for bunts and his mobility. He's just not quite back to 100 percent."

Jordan Ray is a reporter for MLB.com based in Houston. This story was not subject to the approval of Major League Baseball or its clubs.